High-pressure syntheses of TaS3, NbS3, TaSe3, and NbSe3 with NbSe3-type crystal structure |
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Authors: | S Kikkawa N Ogawa M Koizumi Y Onuki |
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Institution: | The Institute of Scientific and Industrial Research, Osaka University, Osaka 565, Japan;Saitama Institute of Technology, Fusaiji Okabe, Saitama 369-02, Japan |
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Abstract: | Transition metal trichalcogenides TaSe3, TaS3, NbSe3 and NbS3 were prepared under the reaction conditions of 2 GPa, 700°C, 30 min. NbSe3 is exactly the same as that obtained in the usual sealed-tube method. The other products are modifications of each usual phase. They have crystal structures very similar to that of NbSe3. The lattice parameters are a = 10.02Å, b = 3.48 Å, c = 15.56 Å, β = 109.6° for TaSe3, a = 9.52 Å, b = 3.35 Å, c = 14.92 Å, β = 110.0° for TaS3, and a = 9.68 Å, b = 3.37 Å, c = 14.83 Å, β = 109.9° for NbS3. In spite of the similarity in their crystal structures, these high-pressure phases show a variety of electrical transport properties. TaSe3 is a superconductor having Tc at 1.9 K. TaS3 is a semiconductor with two transitions at 200 and 250 K. NbS3 is a semiconductor with Ea = 180 MeV. |
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Keywords: | To whom correspondence should be addressed |
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